Several devices for depalletting flexible items are known in the prior art. German DE-OS 38 35 032, corresponding to U.S. Pat. No. 5,102,292 discloses a device for destacking blanks of paper, pasteboard, cardboard, plastic, etc. stacked in blocks. The individual blank blocks are lifted from their respective bases by means of a plunging tool, with the plunging tool being supported on a base for exact positioning immediately prior to being inserted into the blank block. When one blank block has been lifted and carried away, the device either travels to a next blank block or the latter is positioned at the point where the one that has just been transported away was located. The plunging tool is formed by a flexible tongue which, during a destacking process, is initially supported on a solid support and must be pivoted relative to its perpendicular direction of motion. In order for the tongue to penetrate more simply between the parts or beneath the blank block, compressed air is blown between the individual parts, forming an engagement gap for the tongue.
In other known devices for depalletting flexible parts, a gripper unit is in the form of a suction gripper. German DE-AS 25 49 264 shows a device for separating stacked bags, with the bags being picked up by a sucker. German DE-OS 37 42 637 describes another device for removing individual empty bags from a pallet. The gripper unit in this device also is made in the form of a sucker. According to German DE-PS 32 42 181, the device is designed so that a plastic bag is lifted in one corner area by suction, then pivoted through approximately 90.degree., and then lifted off the bag stack beneath. The presence of a suction gripper for picking up a single item is common to all of these devices. However, these devices suffer from an inability to pick up a stack or pick several flexible parts at once.
Devices are also known, for example from German DE-OS 38 05 974 that permit stacks or individual flexible parts to be picked up. This is accomplished by fork tines of a fork lift either underrunning the pallet on which the flexible parts are located or underrunning the flexible parts themselves, and lifting them off the stack located beneath. This solution is especially disadvantageous if the parts are stacked in different stack patterns or if the parts are so shaped that they can snag beneath one another, as for example with valve bags. Picking up open stacks of parts not bound together is not possible since the parts simply slide off the fork tines.
The goal of the present invention is to design a device according to the species in such fashion that with a design advantageous for use, picking up flexible flat parts both individually and in open stacks is possible in a safe and accurate fashion.
This goal is achieved by the invention recited in the main claim. The subclaims show advantageous improvements.